Coburn, 65, an obstetrician, has said that he was battling a strong recurrence of cancer. He did not, however, say cancer was the reason he would be stepping down.

Known for his annual "Wastebook" of excess spending by the federal government, he is in his ninth year in the Senate and had served six years in the House. His term expires in 2016.

"Carolyn and I have been touched by the encouragement we’ve received from people across the state regarding my latest battle against cancer," he said, referring to his wife of nearly 45 years. "But this decision isn’t about my health, my prognosis or even my hopes and desires.

"My commitment to the people of Oklahoma has always been that I would serve no more than two terms. Our founders saw public service and politics as a calling rather than a career. That’s how I saw it when I first ran for office in 1994, and that’s how I still see it today.

"I believe it’s important to live under the laws I helped write, and even those I fought hard to block."

Coburn's announcement marks a change of plans, Politico reports. He told the website earlier this month that he was "plenty healthy enough to serve out my term," but cautioned in an interview that the situation could change.

"The decision I make will be made in conjunction with my family as to how I can best implement and impact things," he said the in Politico interview. "And if I don’t think I can, I won’t."

Coburn’s decision is expected to create a special election to fill out the remainder of his term in Oklahoma, Politico reports.

Sen. Tom Coburn said late Thursday that he was not finishing his term and retiring after this November's elections.
After much prayer and consideration, I have decided that I will leave my Senate seat at the end of this Congress, the Oklahoma Republican...